<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
</head>
<body>
	
</body>
</html>
<script>
	//返回圆周率（约等于3.14159）
	console.log(Math.PI);

	//返回绝对值
	console.log
</script>